New solar islands could turn oceanic CO2 back into clean fuels

A proposed new model for turning CO2 absorbed by the oceans back into clean fuels could help end our reliance on fossil fuels and reduce the effects of climate change. The ambitious new technology could be revolutionary but is still theoretical and unproven. So what are its chances of succeeding and how big an impact can it really make?

solar islands
Artists concept of the solar islands proposed in the new plan (Novaton)

Whether you are willing to admit it or not our planet is in the midst of a climate catastrophe. As a result researchers and governments from around the world are spending more money and time on looking for new technologies and innovative ideas to help tackle the problem. At the top of the list is creating clean energy to replace our reliance on fossil fuels and reduce the serious effects they have on our global ecosystem. However no matter how hard we might try to create clean energy to power our homes, cars and sustain our daily lives there are still some things that need liquid fuels to work. These include aeroplanes, lorries and cargo ships that are proving harder to switch to an electrical power source, at least for the time being. But a newly proposed method using futuristic solar islands could create fuel to power our transportation from the dissolved CO2 in the oceans put there by fossil fuels. By turning dissolved oceanic CO2 back into fuels we won’t stop polluting our planet but we can stop increasing the damage and significantly slow down the rate of climate breakdown, particularly in our oceans. So how does this new model work and will it actually succeed in making a difference?

‘Solar islands’

The new plan was published in a recent PNAS paper by a team of researchers from universities in Switzerland and Norway. Their new model revolves around floating solar factories or ‘islands’ that feed energy into a centralised plant that converts oceanic CO2 to liquid methanol. The islands in question may look like something from a futuristic sci-fi movie but are actually already well within our technological capacity. The proposed design is for 100m diameter islands covered almost completely with solar panels and surrounded by floatation aids. The idea is to use a total of 70 of these islands to send electricity to a centralised hard-hulled ship. On board that vessel will be a chemical plant capable of taking seawater and extracting the hydrogen and carbon dioxide needed to create methanol. So the solar islands are really just massive batteries creating clean energy to power what is hopefully an ecologically beneficial process. However the plans also suggest that the islands could double up as fish farms that could help with reducing fishing pressures.

How does it work?

The method put forward by the researchers turns regular seawater into ‘clean’ methanol using 3 major steps. Electrolysis, desalination and fuel production, all of which will take place on a central anchored ship. Electrolysis is the process of using electricity to separate out individual compounds from a larger solution. In this case seawater is being separated into hydrogen (H) from water (H2O) and carbon dioxide (CO2) which dissolves into the ocean from increasing carbon emissions. The H and CO2 are then later combined to create methanol (CH3OH) which can be used as a transportation fuel for aeroplanes, lorries and cargo ships. The methanol is then transported back to land using smaller ships leaving the anchored vessel to operate continuously. Why then does the seawater have to be desalinated? It is because if you try to electrolyse seawater the salt in it splits to create chlorine as an unwanted and expensive to deal with by-product. Therefore before electrolysis and methanol conversion can take place the seawater must have its salt removed.

fuel ships
Ships similar to this one can be used to transport methanol back to the mainland

How many will we need?

The main issues with this method is that desalination and electrolysis require large amounts of electricity to work. That is why so many solar islands are needed to create enough energy to run it. According to the researchers calculations this method is capable of producing 1.75 tonnes of methanol an hour using 24 megawatts of electricity. Under really sunny conditions the solar factories should also be able to create excess electricity than can help it run at night. That means that every year a cluster of 70 solar islands could produce 15,300 tonnes of methanol per year. Therefore to completely replace fossil fuels used for transportation a grand total of 170,000 solar islands with accompanying vessels will be needed. If we wanted to go even further and completely replace fossil fuels it would mean millions of solar islands covering around 1.5% of our oceans. That is a lot of solar panels! But if it works it should be worth it in the long run both financially and ecologically.

Potential problems

Whilst this proposal could be revolutionary it is also extremely ambitious, untested and still has some kinks to iron out. Firstly it has to work and until the islands are built and the processes set up we just won’t know if it works like the researchers believe it should. As part of this they will also have to find a suitable catalyst for the conversion of methanol. When making methanol on land copper–zinc–aluminium catalysts are used but require high pressures and temperatures. This can be dangerous on a boat carrying large amounts of combustible liquid and can create carbon monoxide as a by-product. Using smaller reactors or switching to alternative catalysts such as selective nickel–gallium compounds might alleviate these problems, but they still need to be tried and tested. The process also has to be economically viable. As much as creating clean energy is a priority unless companies can turn a profit to sustain the process it will never get off the ground. Therefore to work the island clusters cannot cost more than £70 million each and it is unknown if this is achievable at this time.

aeroplane
Aeroplanes like this could potentially be run off methanol converted from seawater

As well as financial and logistical issues the process must also take into consideration any potential impacts on wildlife. The whole point of the plan is to remove excess CO2 from the ocean which would be extremely beneficial to marine life. But if doing that creates other problems elsewhere then it becomes a much less appealing option. Potential wildlife impacts include fuel spills, increased anthropogenic noise from shipping, air breathers like cetaceans and turtles getting caught beneath the islands, reduced sunlight to some areas of the ocean and lower phytoplankton levels at the surface. We will not know the full extent of any of these problems until a trial cluster is set up and production is in full flow. Therefore during the testing stage these issues must all be studied and addressed to make sure the process remains ecologically beneficial.

Zero gain

It is important to keep in mind that this method of methanol production will not fix problems associated with climate change or reverse serious changes to ocean systems. However it could significantly reduce a further runaway effect and give us more time to tackle the big problems. CO2 concentrations are 125 time greater in the ocean than they are in the atmosphere. As a result oceans have become more acidic and a cascade of environmental issues have developed because of this. By taking CO2 out of the ocean on a large scale it will prevent the problem becoming worse in the short term. Using recycled methanol instead of fossil fuels completely won’t reduce levels of atmospheric pollutants but if done right could lead to a zero net gain of emissions. Until technology allows for things like aeroplanes to become powered by clean energy this may be the best case scenario for slowing down the climate catastrophe. Although there are still problems with this new plan if they can be resolved this technology could have a bright future and is well worth keeping an eye on for any environmentalist.


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